Behaviour of expansive clay when it absorbs water

Abstract

Geotechnical engineers have been having problem with soils due to the expansive nature of clay. This is mainly due to the minerals that exist in clay. The affinity to water of montmorillonite in clay has caused different swelling pressures due to the variations in the moisture content of the soils. Expansive soils have the potential for shrinking and swelling under moisture variations as stated by Nelson.

There are three objectives for this project. The first objective is to investigate what are the effects of the percentage of bentonite on the swelling pressure. The other objective is to investigate what are the effects on the swelling pressure when the water content changes. The last objective is to investigate the volumetric change of clay when its bentonite content increases. In this project, Bentonite as it belongs to the montmorillonite group. Bentonite shows a significant increase in volume and exerts pressure to the surrounding soil when it absorbs water. In order to simulate the swelling characteristics of clay, Sodium Bentonite and Kaolinite is being used. As Kaolinite is inert to water, we will investigate the effects of bentonite on the swelling pressure and the volumetric change that it exerts when its water content increases.

From the results which have been gathered, it was found that as the percentage of the bentonite in the sample increase, the swelling pressure increases. It was found that the free swell of the clay sample increases as the percentage of the bentonite in the sample increases. The other result found is that as the amount of water content increases, the swell pressure caused by the sample decreases. With the knowledge of how effects of the bentonite changes in relation to water content will enables prediction of the potential damages that are likely to occur on structures build on such ground so that alternative precaution can be taken in consideration when constructing them. Moreover, with the knowledge of the potential problem that will be caused by the bentonite, we are able to take precaution to avoid structures that are built on it to be damaged.